free the PG(auto_prepend_file) only when tideways.auto_prepend_library is set
free the PG(auto_prepend_file) only when tideways.auto_prepend_library is set

when user has it's own auto_prepend_file and sets tideways.auto_prepend_library to 0
the PG(auto_prepend_file) will be freed and set to NULL, it will break
the user's configuration

tideways/php-profiler-extension,tideways/php-profiler-extension